1. Field of the Invention
The present invention relates to a universal blood pressure cuff for an automated blood pressure monitor system.
2. Description of Related Art
Arterial blood pressure has been found to be an important indicator of a person's health and its measurement has become a part of every complete physical examination. Blood pressure monitoring is used to screen patients for hypertension and other illnesses. In particular, an inappropriate low pressure may signify a medical emergency while an inappropriate high blood pressure is a marker for hypertension which has been found to be a major risk factor for premature cardiovascular and other vascular diseases. In addition, diabetics have now been encouraged to regularly monitor their blood pressure in order to reduce medical complications caused by diabetes.
Therefore, the requirement for the use of blood pressure monitors in the home has increased substantially and therefore the need for improved and intuitive blood pressure monitors has become even more necessary.
FIG. 1 is a block diagram of a conventional blood pressure monitor 1 including a CPU 2 for controlling blood pressure monitor 1, a display 3 for displaying status information and the blood pressure measured by blood pressure monitor 1, operation switches 4 for activating and otherwise controlling blood pressure monitor 1, a pump 5 connected to a cuff 6 having predetermined dimensions through a predetermined deflation rate valve 7. Blood pressure monitor 1 also includes a pressure sensor 8 that measures the pressure within cuff 6 and provides that information to CPU 2 for display on display 3. Blood pressure monitor 1 also includes a power supply 9 and an optional buzzer 10, which provides audible signaling to the user as needed by blood pressure monitor 1.
Cuff 6 in the conventional blood pressure monitor 1 is specifically designed for use only with blood pressure monitor 1 and has predetermined dimensions including width, length, volume, etc. Historically, cuff size has been a very controversial subject and has caused the need for guidelines that are recommended in regards to the relationship between the patient's arm circumference to bladder coverage and the geometry of the bladder itself in order for the blood pressure monitor 1 to obtain a correct reading. A requirement to have a predetermined cuff 6 has created issues of being able to have one blood pressure monitor that will allow the use of almost any size cuff without having to do a manual adjustment each time. Manual adjustment would be required due to the fact that conventional blood pressure monitors require not only a constant deflation rate but a deflation rate that is within a specific range, typically, three to six mmHg/sec. For example, when a blood pressure monitor is set for predetermined cuff 6 and a larger cuff is used, the deflation rate would be so slow that it would be very uncomfortable to the patient. In addition, if a smaller cuff than predetermined cuff 6 is used, the deflation rate would be increased causing inaccurate results.
It is also known that there is significant range of arm circumferences across the population of patients resulting in the need for different size cuffs for different arm circumferences that are still required to fit within the recommended guidelines. For example, conventional blood pressure monitors have a cuff 6 with a circumference range of 20 cm to 30 cm. If the arm circumference is 25 cm, then the pressure reading might be right, but if the arm circumference is 30 cm, blood pressure monitor 1 may produce an acceptable error due to "undercuffing". In addition, if the arm circumference is 20 cm blood pressure monitor 1 would produce an acceptable error due to "overcuffing". These measurements may still be accurate but would not be precise. To use blood pressure monitor 1 outside the above range would require the use of different size predetermined cuffs 6, smaller cuffs for smaller arm circumferences and larger cuffs for larger arm circumferences. To provide such an assortment of arm circumference sized cuffs is a burden to the healthcare worker and adds additional costs to the blood pressure monitor.
Hence, it is necessary to provide a universal blood pressure cuff that can be used on a range of arm circumferences that represent the typical population of patients.